Systems and methods for defining user-discernable acoustical settings

ABSTRACT

In accordance with embodiments of the present disclosure, a system may include a cooling subsystem comprising at least one air mover configured to generate a cooling airflow in the system and a thermal manager communicatively coupled to the cooling subsystem and configured to: (i) determine a minimum air mover speed and maximum air mover speed based on a minimum sound level and a maximum sound level for sound generated by the at least one air mover; and (ii) operate the at least one air mover in accordance with thermal requirements of the system subject to the maximum air mover speed and the minimum air mover speed.

TECHNICAL FIELD

The present disclosure relates in general to information handlingsystems, and more particularly to thermal management of an informationhandling system and defining user-discernable acoustical settingsassociated with air movers used to provide thermal management.

BACKGROUND

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option available to users is information handling systems. Aninformation handling system generally processes, compiles, stores,and/or communicates information or data for business, personal, or otherpurposes thereby allowing users to take advantage of the value of theinformation. Because technology and information handling needs andrequirements vary between different users or applications, informationhandling systems may also vary regarding what information is handled,how the information is handled, how much information is processed,stored, or communicated, and how quickly and efficiently the informationmay be processed, stored, or communicated. The variations in informationhandling systems allow for information handling systems to be general orconfigured for a specific user or specific use such as financialtransaction processing, airline reservations, enterprise data storage,or global communications. In addition, information handling systems mayinclude a variety of hardware and software components that may beconfigured to process, store, and communicate information and mayinclude one or more computer systems, data storage systems, andnetworking systems.

As processors, graphics cards, random access memory (RAM) and othercomponents in information handling systems have increased in clock speedand power consumption, the amount of heat produced by such components asa side-effect of normal operation has also increased. Often, thetemperatures of these components need to be kept within a reasonablerange to prevent overheating, instability, malfunction and damageleading to a shortened component lifespan. Accordingly, thermalmanagement systems including air movers (e.g., cooling fans and blowers)have often been used in information handling systems to cool informationhandling systems and their components. Various input parameters to athermal management system, such as measurements from temperature sensorsand inventories of information handling system components are oftenutilized by thermal management systems to control air movers and/orthrottle power consumption of components in order to provide adequatecooling of components.

By their very nature of being mechanical devices, air movers maygenerate sound, the level of sound being a function of the speed atwhich the air mover is rotating. For example, at high rotational speeds,an air mover may generate high levels of sound which may be unsuitablefor some environments (e.g., an office setting) while being suitable forother environments (e.g., a data center filled with many informationhandling systems). As another example, changes in sound levels due tochanges in fan speed in response to thermal control needs of aninformation handling system may also be undesirable, as changes in anambient sound level may be distracting in some environments.

Thus, a need exists for users to intelligently control acoustical outputof air movers while also maintaining adequate cooling capability.However, users may not often know how acoustical features correlate witha usage environment (e.g., as may be the case where an administratorprovisions information handling systems for use at a remote office) andmay not often know how system designers set tradeoffs between acousticsand thermal control responses based on presumed usage models.Furthermore, an actual usage environment may differ from assumptionsapplied in design of a system. Thus, to maintain a desired level ofnoise from a cooling system while maintaining an adequate level ofcooling, a user may need to apply significant trial and error to achieveoptimum settings.

SUMMARY

In accordance with the teachings of the present disclosure,disadvantages and problems associated with thermal management of aninformation handling system may be reduced or eliminated.

In accordance with embodiments of the present disclosure, a system mayinclude a cooling subsystem comprising at least one air mover configuredto generate a cooling airflow in the system and a thermal managercommunicatively coupled to the cooling subsystem and configured to: (i)determine a minimum air mover speed and maximum air mover speed based ona minimum sound level and a maximum sound level for sound generated bythe at least one air mover; and (ii) operate the at least one air moverin accordance with thermal requirements of the system subject to themaximum air mover speed and the minimum air mover speed.

In accordance with these and other embodiments of the presentdisclosure, a method may include determining a minimum air mover speedand a maximum air mover speed for at least one air mover of a coolingsystem configured to generate a cooling airflow in a system based on aminimum sound level and a maximum sound level for sound generated by theat least one air mover and operating the at least one air mover inaccordance with thermal requirements of the system subject to themaximum air mover speed and the minimum air mover speed.

In accordance with these and other embodiments of the presentdisclosure, an article of manufacture may include a non-transitorycomputer readable medium and computer-executable instructions carried onthe computer readable medium, the instructions readable by a processor,the instructions, when read and executed, for causing the processor todetermine a minimum air mover speed and a maximum air mover speed for atleast one air mover of a cooling system configured to generate a coolingairflow in a system based on a minimum sound level and a maximum soundlevel for sound generated by the at least one air mover and operate theat least one air mover in accordance with thermal requirements of thesystem subject to the maximum air mover speed and the minimum air moverspeed.

Technical advantages of the present disclosure may be readily apparentto one skilled in the art from the figures, description and claimsincluded herein. The objects and advantages of the embodiments will berealized and achieved at least by the elements, features, andcombinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are examples and explanatory and arenot restrictive of the claims set forth in this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, in which like referencenumbers indicate like features, and wherein:

FIG. 1 illustrates a perspective view of an example information handlingsystem, in accordance with embodiments of the present disclosure;

FIG. 2 illustrates a mathematical model for estimating component thermalperformance and setting thermal controls, in accordance with embodimentsof the present disclosure;

FIG. 3 illustrates a plan view of an example information handlingsystem, in accordance with embodiments of the present disclosure;

FIG. 4 illustrates a user interface for managing thermal conditions of aserver information handling system with stored configuration settings ofsubsystems within the information handling system, in accordance withembodiments of the present disclosure;

FIGS. 5A and 5B illustrate a user interface for estimating systemairflow and exhaust temperature based upon conservation of energy withinan information handling system housing, in accordance with embodimentsof the present disclosure;

FIG. 6 illustrates a user interface for setting cooling airflow to meetdefined conditions, such as temperature defined as a fixed requirement,a measurement read from a sensor or a measurement leveraged from avirtual sensor reading, in accordance with embodiments of the presentdisclosure;

FIG. 7 illustrates a conversion of determined airflow rates to coolingfan pulse width modulation settings, in accordance with embodiments ofthe present disclosure;

FIG. 8 illustrates a flow chart of an example method for defining userdiscernable acoustical settings, in accordance with embodiments of thepresent disclosure; and

FIG. 9 illustrates a graph of example acoustical category bands that mayselected to set minimum and maximum values of air mover speeds, inaccordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

Preferred embodiments and their advantages are best understood byreference to FIGS. 1 through 8, wherein like numbers are used toindicate like and corresponding parts.

For the purposes of this disclosure, an information handling system mayinclude any instrumentality or aggregate of instrumentalities operableto compute, classify, process, transmit, receive, retrieve, originate,switch, store, display, manifest, detect, record, reproduce, handle, orutilize any form of information, intelligence, or data for business,scientific, control, entertainment, or other purposes. For example, aninformation handling system may be a personal computer, a PDA, aconsumer electronic device, a network storage device, or any othersuitable device and may vary in size, shape, performance, functionality,and price. The information handling system may include memory, one ormore processing resources such as a central processing unit (CPU) orhardware or software control logic. Additional components of theinformation handling system may include one or more storage devices, oneor more communications ports for communicating with external devices aswell as various input and output (I/O) devices, such as a keyboard, amouse, and a video display. The information handling system may alsoinclude one or more buses operable to transmit communication between thevarious hardware components.

For the purposes of this disclosure, computer-readable media may includeany instrumentality or aggregation of instrumentalities that may retaindata and/or instructions for a period of time. Computer-readable mediamay include, without limitation, storage media such as a direct accessstorage device (e.g., a hard disk drive or floppy disk), a sequentialaccess storage device (e.g., a tape disk drive), compact disk, CD-ROM,DVD, random access memory (RAM), read-only memory (ROM), electricallyerasable programmable read-only memory (EEPROM), and/or flash memory; aswell as communications media such as wires, optical fibers, microwaves,radio waves, and other electromagnetic and/or optical carriers; and/orany combination of the foregoing.

For the purposes of this disclosure, information handling resources maybroadly refer to any component system, device or apparatus of aninformation handling system, including without limitation processors,buses, memories, I/O devices and/or interfaces, storage resources,network interfaces, motherboards, integrated circuit packages;electro-mechanical devices (e.g., air movers), displays, and powersupplies.

FIG. 1 illustrates a perspective view of an example information handlingsystem 10, in accordance with embodiments of the present disclosure. Asshown in FIG. 1, information handling system 10 may comprise a serverbuilt into a housing 12 that resides with one or more other informationhandling systems 10 in a rack 14. Rack 14 may comprise a plurality ofvertically-stacked slots 16 that accept information handling systems 10and a plurality of power supplies 18 that provide electrical energy toinformation handling systems 10. In a data center environment, rack 14may receive pretreated cooling air provided from a floor vent 20 to aidremoval of thermal energy from information handling systems 10 disposedin rack 14. Power supplies 18 may be assigned power based uponavailability at the data center and may allocate power to individualinformation handling systems 10 under the management of a chassismanagement controller (CMC) 22. CMC 22 may aid coordination of operatingsettings so that information handling systems 10 do not exceed thermalor power usage constraints.

Housing 12 may include a motherboard 24 that provides structural supportand electrical signal communication for processing components disposedin housing 12 that cooperate to process information. For example, one ormore central processing units (CPUs) 26 may execute instructions storedin random access memory (RAM) 28 to process information, such asresponses to server requests by client information handling systemsremote from information handling system 10. One or more persistentstorage devices, such as hard disk drives (HDD) 30 may store informationmaintained for extended periods and during power off states. A backplanecommunications manager, such as a PCI card 32, may interface processingcomponents to communicate processed information, such as communicationsbetween CPUs 26 and network interface cards (NICs) 34 that are sentthrough a network, such as a local area network. A chipset 36 mayinclude various processing and firmware resources for coordinating theinteractions of processing components, such as a basic input/outputsystem (BIOS). A baseboard management controller (BMC) 38 may interfacewith chipset 36 to provide out-of-band management functions, such asremote power up, remote power down, firmware updates, and powermanagement. For example, BMC 38 may receive an allocation of power fromCMC 22 and monitor operations of the processing components ofinformation handling system 10 to ensure that power consumption does notexceed the allocation. As another example, BMC 38 may receivetemperatures sensed by temperature sensors 40 and apply the temperaturesto ensure that thermal constraints are not exceeded.

A thermal manager 42 may execute as firmware, software, or otherexecutable code on BMC 38 to manage thermal conditions within housing12, such as the thermal state at particular processing components orambient temperatures at discrete locations associated with housing 12.Thermal manager 42 may control the speed at which air movers 44 (e.g.,cooling fans or cooling blowers) rotate to adjust a cooling airflow ratein housing 12 so that heat is removed at an appropriate temperature, soas to reduce overheating of a CPU 26 or prevent an excessive exhausttemperature as measured by an outlet temperature sensor 40. In the eventthat air movers 44 cannot provide sufficient cooling airflow to meet athermal constraint, thermal manager 42 may reduce power consumption atone or more of the processing components to reduce the amount of thermalenergy released into housing 12, such as by throttling the clock speedof one or more of CPUs 26. Thermal manager 42 may respond to extremethermal conditions that place system integrity in jeopardy by shuttingdown information handling system 10, such as might happen if floor vent20 fails to provide treated air due to a data center cooling systemfailure.

In order to more effectively manage thermal conditions associated withhousing 12, thermal manager 42 may apply conservation of energy toestimate thermal conditions at discrete locations associated withinhousing 12 and then use the estimated thermal conditions for moreprecise control of the overall thermal state of information handlingsystem 10. For example, thermal manager 42 may perform one or moreenergy balances based upon available measures of power consumption,cooling fan speed, and sensed thermal conditions to estimateintermediate temperatures at discrete locations within housing 12. Theestimated intermediate temperatures may provide more precise control ofthe thermal conditions at discrete locations to maintain thermalconstraints, such as maximum ambient temperatures of components that donot include temperature sensors or maximum inlet temperatures forcomponents downstream in the cooling airflow from the estimated ambienttemperature. Estimated intermediate temperatures may be applied in anoverall system conservation of energy model so that fan speed andcomponent power consumption are determined to maintain thermalconstraints, such as maximum exhaust temperatures. Thermal manager 42may estimate discrete thermal conditions at locations within housing 12by applying available component configuration information, such as acomponent inventory kept by BMC 38, and sensed, known, or estimatedpower consumption of the components. For example, BMC 38 may use actualpower consumption of components or subassemblies if actual powerconsumption is available, known power consumption stored in the BMCinventory for known components, or estimated power consumption basedupon the type of component and the component's own configuration. Anexample of estimated power consumption is a general estimate of powerconsumption stored in BMC 38 for unknown PCI cards 32 with the generalestimate based upon the width of the PCI card, i.e., the number of linkssupported by the PCI card. In one embodiment, as estimated intermediatethermal conditions are applied to generate fan and power consumptionsettings, a self-learning function may compare expected results andmodels to component and subassembly thermal characteristics so that moreaccurate estimates are provided over time.

FIG. 2 illustrates a mathematical model for estimating component 46thermal performance and setting thermal controls, in accordance withembodiments of the present disclosure. According to the law ofconservation of energy, the total energy state of an informationhandling system is maintained as a balance of the energy into the systemand the energy out of the system. The energy balance may be broken intoa sum of a plurality of components 46 wherein each component 46 has aknown or estimated power consumption that introduces thermal energy intothe information handling system. The system energy balance becomes theenergy into the system as reflected by an airflow inlet temperature, thethermal energy released by the sum of the components 46 that consumepower in the system, and the energy out of the system as reflected by anairflow exhaust temperature. Energy removed from the system may relateto the mass flow rate of air flowing through the system and thecoefficient for energy absorption of the cooling airflow. Simplified forthe coefficient that typically applies to atmospheric air, the energyreleased by electrical power consumption may be equal to airflow incubic feet per minute divided by a constant of 1.76 and multiplied bythe difference between the exhaust temperature and inlet temperature.Alternatively, again simplified for the coefficient that typicallyapplies to atmospheric air, the energy released by electrical powerconsumption may be equal to a linear airflow velocity in linear feet perminute (which may be calculated as a cubic airflow rate in cubic feetper minute multiplied by an area of an inlet of a component of interest(e.g., cross sectional area of inlet of a card)) divided by a constantof 1.76 and multiplied by the difference between the exhaust temperatureand inlet temperature. Thermal manager 42 may apply one or both of theseformulas to set cooling fan speed to meet exhaust temperatureconstraints. For internal components and subassemblies, thermal manager42 may determine a minimum fan speed to keep ambient temperature of acomponent within a desired constraint by determining an “inlet”temperature estimated for air as it arrives at the component based uponpower consumption of other components in the airflow before the airarrives at the component of interest. The increase in temperatureexhausted at the component of interest may be estimated based upon thepower consumed by the component of interest and the cooling airflowrate. Thus, a fan speed may be set that prevents an “exhaust” from thecomponent of interest that is in excess of thermal constraintsassociated with the component. Alternatively, estimated temperatures atintermediate components may be summed and applied to set a fan speedthat achieves a desired overall system thermal condition, such as anexhaust temperature constraint.

Applying conservation of energy and component power consumption tomanage thermal conditions may allow more precise control of thermalconditions and discrete control within an information handling systemhousing even where measurements of actual thermal conditions by atemperature sensor are not available. A modular energy balance thermalcontroller may allow combined serial energy balances to account for theeffect of reduced inlet temperatures when increasing speeds fordownstream energy balances. This flexibility may be provided by usingenergy balances independently to solve for either exhaust temperature orairflow on a system-wide basis or at discrete locations within a system.Subsystem power consumption based upon a component or collection ofcomponents may allow for estimation of upstream preheat for othercomponents within an information handling system housing. For example,components that do not dissipate substantial heat by power consumptionmay be scaled to have a reduced impact on airflow temperatures. Oneexample of such a component is a cooling fan, which dissipates 60 to 80%of power consumption as heat and 20 to 40% as air moving, but isgenerally ignored with conventional thermal controls. By adding fanpower and scaling to match efficiency for the system, a more precisepicture of thermal conditions within a housing may be provided.Isolating power consumption of specific regions, subsystems orcomponents of interest, such as PCI cards, may allow the power readingsfor the subsystems to include static power from non-relevant componentsthat are accounted for by subtracting a static power value. Assigningscaled values that relate heat dissipation and power consumption foreach subsystem may provide more exact estimates of thermal conditionsand more precise control of airflow and power settings based uponpreheat that occurs in the airflow as the airflow passes through thehousing. Approaching thermal management based upon a serial summation ofsubsystem thermal conditions supports the use of static values forselected subsystems to subtract thermal overhead or exclude dynamicreadings, such as to control fan speed to achieve a static readinginstead of monitoring an available dynamic reading.

Using subsystem thermal condition estimates may aid in achieving moreaccurate fan speed settings for a desired exhaust constraint sinceairflow-to-fan speed relationships are set based on actual systemconfiguration and component power consumption. Summed energy balances ofdiscrete subsystems disposed in a housing may differentiate thermalcontrol based on hardware inventory, system state, or system events toenhance control accuracy. Airflow may be scaled to account for componentcount based upon active components and functions being performed at thecomponents during control time periods. When solving for airflowsettings needed to meet a component or system-wide thermal constraint,the inlet or exhaust temperature may generally be a fixed requirementthat aligns with a temperature limit so that selectively setting staticvalues allows derivation of control values without using availabledynamic values. Dynamically calculated inlet ambient with a fixed staticexhaust ambient or a fixed inlet ambient and a dynamically calculatedexhaust ambient may provide a better estimate of system airflow. Aspower use fluctuates, feedback and feed forward control of thermalconditions based on average power consumption may dampen cooling fansetting fluctuations that occur when fan settings are made based uponinstantaneous power readings alone. Averaging measured fan speeds mayalso help to simplify correlations and to “learn” thermalcharacteristics of subsystems as thermal conditions respond over time tochanges in power consumption at various subsystems. For example, eachfan within a housing can run at different pulse width modulation (PWM)speed settings in which a speed of a fan is based on a duty cycle of aPWM signal received by the fan. Calculating an average PWM fromindividual fan PWM speed settings may allow a PWM duty cycle to airflowrelationship. During operating conditions that have limited availabilityof dynamically sensed thermal conditions, such as at startup, during fanfailure, during sensor failure, and during baseline cooling, estimatedsubsystem thermal conditions based upon subsystem power consumption mayprovide a model for fan speed settings. Generally, fan speed settingcontrol based upon a summation of estimated and/or actual subsystemthermal conditions may allow defined minimum fan speeds for asystem-wide constraint with supplemental cooling of critical componentsbased on closed loop feedback.

FIG. 3 illustrates a plan view of example an information handling system10, in accordance with embodiments of the present disclosure. Externalair drawn into information handling system 10 may have an ambienttemperature (T_(AMBIENT)) measured by an inlet temperature sensor 40 andan airflow rate determined by the speed at which one or more coolingfans spin. As the cooling airflow passes through housing 12, it mayabsorb thermal energy resulting in a preheat of the airflow fordownstream components. The cooling airflow may be forced frominformation handling system 10 at an exhaust with an exhaust temperature(T_(EXHAUST)) fixed at thermal constraint (e.g., 70° C.) as arequirement and/or measured by an exhaust temperature sensor 40. Thermalmanager 42 may adapt cooling fan speed so that the cooling airflowtemperature T_(EXHAUST) maintains a thermal constraint (e.g., 70° C.)

As shown in FIG. 3, a virtual thermal sensor 48 may be generated bythermal manager 42 at a location in information handling system 10 thatreceives preheated airflow, such as airflow that has passed by CPUs 26.Thermal manager 42 may apply configuration information stored in BMC 38to determine the components that preheat airflow to virtual thermalsensor 48 and may determine power consumed by the components to arriveat a virtual temperature measured by virtual thermal sensor 48. Forexample, thermal manager 42 may apply power consumed by CPUs 26 andstatic power consumption associated with other preheat components todetermine by conservation of energy the ambient temperature of airexhausted from CPUs 26 to arrive at the virtual temperature. The virtualtemperature may then be used as an inlet temperature to a PCI cardsubsystem 32 so that an ambient temperature of PCI card subsystem 32 iscomputed based upon energy consumed by PCI card subsystem 32. PCI cardsubsystem 32 may exhaust air at temperature T_(EXHAUST) measured byexhaust sensor 40 so that control of the ambient temperature within PCIcard subsystem 32 provides control of the overall system exhaust. Theincrease in thermal energy caused by PCI card subsystem 32 as reflectedby the increase from the virtual temperature to the exhaust temperaturemay be estimated using conservation of energy applied to the energyconsumption of PCI card subsystem 32. Generally, PCI card subsystem 32power consumption may be measured directly based upon power assigned bya power subsystem or estimated with a static value. Alternatively, powerconsumption may be derived from estimates using conservation of energyapplied to known power consumption and thermal conditions in housing 12.Thus, the power consumed by PCI card subsystem 32 may be dynamicallydetermined by actual measurements of power usage, by stored power usagebased on the inventory of the PCI card maintained in the BMC, or by anestimate of power consumption based upon characteristics of the PCIcard, such as the width of the PCI card.

Having one or more intermediate virtual thermal sensors 48 may provideflexibility in managing system operation by using a virtual temperaturemeasurement as a dynamic thermal control input or a static thermalcontrol constraint. For example, if PCI card subsystem 32 is controlledto have a static value of 50° C., then fan speed and CPU powerconsumptions may be adjusted to maintain that value. If T_(EXHAUST) hasa constraint of 70° C., then excessive temperatures might occur duringlow CPU power usage due to low fan speed settings needed to maintain the50° C. virtual thermal sensor 48 measurement and temperature increasesof greater than 20° C. from PCI card power consumption. In such aninstance, if precise power control is available for desired components,thermal control might focus on T_(EXHAUST) so that the virtualtemperature falls below 50° C. or might focus on power consumption byPCI card subsystem 32 so that less thermal energy is released aftervirtual thermal sensor 48. Typically, PCI card subsystems do not at thistime allow control of thermal energy release, such as by throttling aprocessor clock, however, such capabilities may be introduced for PCIcards or other components in the future. Discrete control of thermalconditions at different locations within information handling system 10may be provided by generating virtual thermal sensors at the desiredlocations and then selectively treating the values as dynamic or staticfor control purposes.

FIG. 4 illustrates a user interface for managing thermal conditions of aserver information handling system with stored configuration settings ofsubsystems within the information handling system, in accordance withembodiments of the present disclosure. Energy balance table 50 mayinclude energy balance parameters for components integral to informationhanding system 10 as well as estimated values for potential replacementcomponents, such as non-specific PCI cards having a width of four oreight lanes. By including configuration match information that relatescomponents to energy consumption, thermal manager 42 may be able toestimate a thermal condition based on detected components and energybalance information associated with such detected components as setforth in energy balance table 50.

FIGS. 5A and 5B illustrate a user interface for estimating systemairflow and exhaust temperature based upon conservation of energy withinan information handling system housing, in accordance with embodimentsof the present disclosure. An exhaust temperature energy balance table52 may apply power, cubic airflow, linear airflow velocity, and sensedtemperature values to estimate thermal states and set control fordesired cubic airflow, linear airflow velocity, and temperatureparameters. A power window 54 may depict a power dissipation calculationperformed for each subsystem having an energy balance number in energybalance table 50. A total system power dissipation may represent poweruse by all desired components, which in this example embodiment mayinclude one or more cooling fans. Scaling factors may be set to adjustthe relative power consumption in various configuration modes inresponse to dynamic power settings. A static power setting may alsoallow control to achieve a desired power setting at a component. A cubicairflow window 56 depicts a mass flow calculation in cubic feet perminute (CFM) and a linear airflow velocity window 57 depicts a linearairflow velocity in linear feet per minute (LFM) for determination ofcubic airflow or linear airflow velocity to achieve the energy balancewith the determined power settings for each component. The exampleembodiment depicted by FIGS. 5A and 5B may estimate cubic airflow,linear airflow velocity, and exhaust temperatures, including withvirtual temperature sensors. In particular, for a given PWM valueassociated with cooling fans, exhaust temperature energy balance table52 may correlate such PWM value to an estimated cubic airflow (e.g., inCFM) and/or an estimated linear airflow velocity (e.g., in LFM) forconfigurations associated with the energy balance number.

Although FIG. 5B shows estimation of linear airflow velocity based oncorrelation from PWM values, in some embodiments, linear airflowvelocity may be determined from the PWM-to-cubic airflow ratecorrelation, by dividing the cubic airflow rate correlated to a PWMvalue by an inlet area of a component of interest (e.g., card). FIG. 7described below may provide mass airflows converted to cooling fan PWMvalues to assign cooling fan rotation speeds based upon individualcomponent configurations adjusted for scaling.

FIG. 6 illustrates a user interface for setting cooling airflow to meetdefined conditions, such as temperature defined as a fixed requirement,a measurement read from a sensor, or a measurement leveraged from avirtual sensor reading, in accordance with embodiments of the presentdisclosure. The user interface of FIG. 6 may be used by thermal manager42 to compute how much airflow is required to cool a component. Thetemperature and power values may be static or dynamic; however, onevalue may be set to static to support control of the other values tomeet a targeted static condition. An airflow energy balance table 60 maysupport mass airflow and exhaust temperature estimates with dynamic orstatic settings in the power consumption of the components. An averagenumber of readings input aids in adjusting for thermal lag related todelays between dissipation of power by components and temperatureimpacts. In the entry for energy balance number EB4 shown in FIG. 6, anexhaust temperature of 70° C. may be set for exhaust from a PCI cardbased upon a static power setting for a lane width of eight lanes. Forexample, a lane width of eight lanes may define an estimated powerconsumption for the card and the 70° C. temperature may define anoverall system safety constraint. The entry sets a static inlettemperature for the PCI card of 55° C., such as might be an input limitfor the PCI card or so that an airflow rate is determined that maintainsthe desired exhaust temperature constraint. Alternatively, the inlettemperature may be dynamic from a physical sensor or from a virtualsensor computed with a conservation of energy estimated based uponupstream component power consumption. If the airflow rate is less thananother airflow rate required at a different location in housing 12, theconstraint may be met without applying the determined airflow rate. Forexample, if the airflow rate to maintain 55° C. exhaust from the CPUs isgreater than the airflow rate required to maintain PCI card thermalconditions, then the CPU airflow rate will apply. In this manner,discrete airflow rates for different portions of information handlingsystem 10 may provide more exact thermal management for componentsdisposed within housing 12.

FIG. 7 illustrates a user interface table 62 for conversion ofdetermined airflow rates to cooling fan pulse width modulation (PWM)settings, in accordance with embodiments of the present disclosure. Forexample, a graph of different levels of cooling airflow and PWM settingsis depicted for different numbers of hard disk drives disposed inhousing 12. Such data may be used to set a scaling factor (value of0.008 under the heading “HDD”) in an energy balance entry for aparticular energy balance number. Thus, given a particular airflowrequirement, whether in CFM or LFM, required cooling fan speeds may becalculated based upon system configuration as detected by BMC 38.

Using the foregoing methods and systems, a cubic airflow rate or linearairflow velocity at a particular point (e.g., at an inlet of PCIsubsystem 32) in information handling system 10, may be estimated basedon cooling fan speed. Such cubic airflow rate or linear airflow rate maybe a “bulk” or average value (e.g., a per PCI slot average value) or aworst case rate (e.g., a value for a “worst case” PCI slot PCI subsystem32). In addition, using the foregoing methods and systems, given arequired cubic airflow rate or linear airflow velocity for a component(e.g., a PCI card), a minimum fan speed required to support suchcomponent may be estimated.

While the foregoing description contemplates using energy balances toestimate a linear airflow velocity in LFM based on a cooling fan PWMvalue, linear airflow velocity in LFM may also be estimated by using anestimate of cubic airflow rate in CFM (e.g., generated using energybalance data from table 52 in FIGS. 5a and 5b ) and an estimatedcross-sectional area through which the flow of air travels.

FIG. 8 illustrates a flow chart of an example method 800 for defininguser discernable acoustical settings, in accordance with embodiments ofthe present disclosure. According to some embodiments, method 800 maybegin at step 802. As noted above, teachings of the present disclosuremay be implemented in a variety of configurations of informationhandling system 10. As such, the preferred initialization point formethod 800 and the order of the steps comprising method 800 may dependon the implementation chosen.

At step 802, thermal manager 42 may receive an indication of anacoustical setting defining user-desired limits (e.g., in terms ofdecibels) of sound level output by air movers 44. In some embodiments,such indication may be individually-configurable minimum and maximumsound levels input by a user. In other embodiments, such indication mayinclude individually-configurable minimum and maximum sound levelsassociated with a plurality of user-selectable ranges or categories ofsound levels. For example, FIG. 9 illustrates a graph of exampleacoustical category bands (e.g., Cat 1, Cat 2, Cat 3, Cat 4, Cat 5) thatmay selected by a user or automatically based on system configuration toset minimum and maximum values of air mover speeds, in accordance withembodiments of the present disclosure.

At step 804, thermal manager 42 may determine a minimum air mover speed(e.g., in terms of a duty cycle of a pulse-width modulated controlsignal) corresponding to the minimum sound level and a maximum air moverspeed corresponding to the maximum sound level. In some embodiments, therespective air mover speed limits corresponding to the respective soundlevel limits may be based on a formula that translates a sound level toa particular air speed. In some of such embodiments, such formula may bebased on testing and/or characterization of air movers. In these andother embodiments, such formula may be updatable in the event air movers44 are upgraded or otherwise modified (e.g., such formula may be storedas part of firmware or a field replaceable unit associated with an airmover 44).

At step 806, thermal manager 42 may determine a maximum cubic airflowbased on the maximum air mover speed by reference to user interfacetable 62 of FIG. 7 or any other suitable approach for translating an airmover speed to the cubic airflow. At step 808, thermal manager 42 may,based on a hardware configuration of information handling system 10,thermal conditions of information handling system 10 (e.g., inlettemperature, outlet temperature, other temperature), and/or thermalparameters set forth in energy balance table 50, exhaust temperatureenergy balance table 52, airflow energy balance table 60, and/or userinterface table 62) identify cooling limits of components of informationhandling system 10 associated with the maximum cubic airflow. At step810, thermal manager 42 may communicate information to a user regardingsuch cooling limits, and in some embodiments may prompt a user to agreeto operate in accordance with such cooling limits.

At step 812, thermal manager 42 may determine power capping limits basedon the cooling limits identified above, so as to not operate componentsof information handling system 10 at power levels for which adequatecooling would be unavailable using the maximum cubic airflow.

At step 814, thermal manager 42 may operate air movers 44 in accordancewith the thermal requirements of components of information handlingsystem 10, subject to the maximum air mover speed and minimum air moverspeed determined above. After completion of step 814, method 800 mayend.

Although FIG. 8 discloses a particular number of steps to be taken withrespect to method 800, method 800 may be executed with greater or fewersteps than those depicted in FIG. 8. In addition, although FIG. 8discloses a certain order of steps to be taken with respect to method800, the steps comprising method 800 may be completed in any suitableorder.

Method 800 may be implemented using one or more information handlingsystems 10, components thereof, and/or any other system operable toimplement method 800. In certain embodiments, method 800 may beimplemented partially or fully in software and/or firmware embodied incomputer-readable media.

In accordance with above systems and methods, air mover speeds forparticular system or user profiles may allow for setting of fan speedsbased on acoustical limits rather than some arbitrary number. Forexample, an information handling system may have a profile which definesan allowable acoustical range which in turn defines an allowable rangeof air mover speeds, similar to the determinations of minimum andmaximum air mover speeds made in method 800. As a specific example, aninformation handling system may have a “maximum performance profile”meaning a cooling system uses higher air mover speeds to ensure greatermargin to thermal specifications and hence least risk to throttling andperformance degradation. Thus, for a system idle air mover speed, thecorrelation between air mover speed limits and acoustical limits, thehighest air mover speed within an acceptable acoustical category may beset to a baseline or “idle” air mover speed.

In addition, in some embodiments an acoustical category band as shown inFIG. 9 may be selected based on a baseline air mover speed. For example,thermal manager 42 may determine that based on a system configuration ofan information handling system 10, that a baseline “idle” air moverspeed of 15% pulse width modulation (PWM) is required to adequately coolinformation handling system 10, which is in acoustical category Cat 2 inFIG. 9. Thus, in such a scenario, acoustical category Cat 2 may beselected by thermal manager 42, and the maximum of air mover speed maybe set to 20% PWM, based on the upper limit of acoustical category Cat 2shown in FIG. 9.

Although the foregoing discusses cubic airflow in terms of cubic feetper minute, other units of measurement may be used (e.g., cubic metersper second). Also, although the foregoing discusses linear airflowvelocity in terms of linear feet per minute, other units of measurementmay be used (e.g., meters per second).

As used herein, when two or more elements are referred to as “coupled”to one another, such term indicates that such two or more elements arein electronic communication or mechanical communication, as applicable,whether connected indirectly or directly, with or without interveningelements.

This disclosure encompasses all changes, substitutions, variations,alterations, and modifications to the example embodiments herein that aperson having ordinary skill in the art would comprehend. Similarly,where appropriate, the appended claims encompass all changes,substitutions, variations, alterations, and modifications to the exampleembodiments herein that a person having ordinary skill in the art wouldcomprehend. Moreover, reference in the appended claims to an apparatusor system or a component of an apparatus or system being adapted to,arranged to, capable of, configured to, enabled to, operable to, oroperative to perform a particular function encompasses that apparatus,system, or component, whether or not it or that particular function isactivated, turned on, or unlocked, as long as that apparatus, system, orcomponent is so adapted, arranged, capable, configured, enabled,operable, or operative.

All examples and conditional language recited herein are intended forpedagogical objects to aid the reader in understanding the disclosureand the concepts contributed by the inventor to furthering the art, andare construed as being without limitation to such specifically recitedexamples and conditions. Although embodiments of the present disclosurehave been described in detail, it should be understood that variouschanges, substitutions, and alterations could be made hereto withoutdeparting from the spirit and scope of the disclosure.

What is claimed is:
 1. A system comprising: a cooling subsystemcomprising at least one air mover configured to generate a coolingairflow in the system; and a thermal manager communicatively coupled tothe cooling subsystem and configured to: receive an indication of anallowable acoustical range for the cooling subsystem, wherein theallowable acoustical range includes a minimum sound level and a maximumsound level for sound generated by the at least one air mover; determinea minimum air mover speed and a maximum air mover speed via a formulabased on the minimum sound level and the maximum sound level for soundgenerated by the at least one air mover; operate the at least one airmover in accordance with thermal requirements of the system subject tothe maximum air mover speed and the minimum air mover speed; identifycooling limits of the cooling subsystem when operating at the maximumair mover speed based on one or more of a hardware configuration of thesystem, thermal conditions of the system, and thermal parametersassociated with the system; determine and apply power consumption limitsto components of the system based on the cooling limits; and in responseto a replacement of an air mover of the at least one air mover with anew air mover, cause the formula to be updated from an original formulato a new formula, wherein the new formula is based on the new air mover.2. The system of claim 1, wherein the thermal manager is configured toidentify the cooling limits of the cooling subsystem when operating atthe maximum air mover speed by: determining a maximum cubic airflowbased on the maximum air mover speed; and determining the cooling limitsbased on the maximum cubic airflow.
 3. The system of claim 1, whereinthe thermal manager is further configured to communicate informationregarding the cooling limits to a user of the system.
 4. The system ofclaim 1, wherein the minimum sound level and the maximum sound level arebased on a configurable setting of a user of the system.
 5. The systemof claim 4, wherein the configurable setting is a user selection fromamong a plurality of acoustical categories, each acoustical categorydefining a corresponding minimum air mover speed and maximum air moverspeed.
 6. The system of claim 1, wherein the minimum sound level and themaximum sound level are based on a performance profile of the system,and a baseline air mover speed is based on at least one of the minimumsound level and maximum sound level associated with the performanceprofile.
 7. A method comprising: receiving an indication of an allowableacoustical range for a cooling system, wherein the allowable acousticalrange includes a minimum sound level and a maximum sound level for soundgenerated by at least one air mover of the cooling system; determining aminimum air mover speed and a maximum air mover speed for the at leastone air mover of the cooling system configured to generate a coolingairflow in a system via a formula based on the minimum sound level andthe maximum sound level for sound generated by the at least one airmover; operating the at least one air mover in accordance with thermalrequirements of the system subject to the maximum air mover speed andthe minimum air mover speed; identifying cooling limits of the coolingsystem when operating at the maximum air mover speed based on one ormore of a hardware configuration of the system, thermal conditions ofthe system, and thermal parameters associated with the system;determining and applying power consumption limits to components of thesystem based on the cooling limits; and in response to a replacement ofan air mover of the at least one air mover with a new air mover, causingthe formula to be updated from an original formula to a new formula,wherein the new formula is based on the new air mover.
 8. The method ofclaim 7, further comprising identifying the cooling limits of thecooling system when operating at the maximum air mover speed by:determining a maximum cubic airflow based on the maximum air moverspeed; and determining the cooling limits based on the maximum cubicairflow.
 9. The method of claim 7, further comprising communicatinginformation regarding the cooling limits to a user of the system. 10.The method of claim 7, wherein the minimum sound level and the maximumsound level are based on a configurable setting of a user of the system.11. The method of claim 10, wherein the configurable setting is a userselection from among a plurality of acoustical categories, eachacoustical category defining a corresponding minimum air mover speed andmaximum air mover speed.
 12. The method of claim 7, wherein the minimumsound level and the maximum sound level are based on a performanceprofile of the system, the method further comprising setting a baselineair mover speed based on at least one of the minimum sound level andmaximum sound level associated with the performance profile.
 13. Anarticle of manufacture, comprising: a non-transitory computer readablemedium; and computer-executable instructions carried on the computerreadable medium, the instructions readable by a processor, theinstructions, when read and executed, for causing the processor to:receive an indication of an allowable acoustical range for a coolingsystem, wherein the allowable acoustical range includes a minimum soundlevel and a maximum sound level for sound generated by at least one airmover of the cooling system; determine a minimum air mover speed and amaximum air mover speed for the at least one air mover of the coolingsystem configured to generate a cooling airflow in a system via aformula based on the minimum sound level and the maximum sound level forsound generated by the at least one air mover; operate the at least oneair mover in accordance with thermal requirements of the system subjectto the maximum air mover speed and the minimum air mover speed; identifycooling limits of the cooling system when operating at the maximum airmover speed based on one or more of a hardware configuration of thesystem, thermal conditions of the system, and thermal parametersassociated with the system; determine and apply power consumption limitsto components of the system based on the cooling limits; and in responseto a replacement of an air mover of the at least one air mover with anew air mover, cause the formula to be updated from an original formulato a new formula, wherein the new formula is based on the new air mover.